This invention relates in general to vehicle brake assemblies and in particular to a brake rotor adapted for use in such a vehicle brake assembly and to a method for producing such a brake rotor.
Most vehicles are equipped with a brake system for slowing or stopping movement of the vehicle in a controlled manner. A typical brake system for an automobile or light truck includes a disc brake assembly for each of the front wheels and either a drum brake assembly or a disc brake assembly for each of the rear wheels. The brake assemblies are actuated by hydraulic or pneumatic pressure generated when an operator of the vehicle depresses a brake pedal. The structures of these drum brake assemblies and disc brake assemblies, as well as the actuators therefor, are well known in the art.
A typical disc brake assembly includes a rotor which is secured to the wheel of the vehicle for rotation therewith. A caliper assembly is slidably supported by pins secured to an anchor bracket. The anchor bracket is secured to a non-rotatable component of the vehicle, such as the vehicle frame. The caliper assembly includes a pair of brake shoes which are disposed on opposite sides of the rotor. The brake shoes are operatively connected to one or more hydraulically actuated pistons for movement between a non-braking position, wherein they are spaced apart from opposed axial sides or braking surfaces of the rotor, and a braking position, wherein they are moved into frictional engagement with the opposed braking surfaces of the rotor. When the operator of the vehicle depresses the brake pedal, the piston urges the brake shoes from the non-braking position to the braking position so as to frictionally engage the opposed braking surfaces of the rotor and thereby slow or stop the rotation of the associated wheel of the vehicle.
A typical disc brake rotor is formed from grey cast iron during a sand mold casting process. The rotor includes a generally hat-shaped body, and an outer annular section which are integrally cast as one-piece during the casting process. This kind of rotor is commonly referred to as a xe2x80x9cfull castxe2x80x9d rotor. In some instances, the rotor is formed with an integrally cast hub, and is referred to as a xe2x80x9cuni-castxe2x80x9d rotor.
In the above rotor constructions, the hat-shaped body includes a mounting surface having a centrally locating pilot hole formed therein during the casting process, and a plurality of lug bolt receiving apertures equally spaced circumferentially about the pilot hole. The lug bolt receiving apertures are formed during a subsequent drilling operation.
The outer annular section of the rotor includes two parallel outer surfaces which define a pair of brake friction surfaces. The brake friction surfaces can be cast as a single solid brake friction plate, or can be cast as a pair of brake friction plates disposed in a mutually spaced apart relationship by a plurality of ribs or fins to produce a xe2x80x9cventedxe2x80x9d rotor. The brake friction surfaces, as well as other selected surfaces of the rotor including the lug bolt receiving apertures, are typically machined by two xe2x80x9croughxe2x80x9d finishing operations followed by a single xe2x80x9cfinishxe2x80x9d machining operation. The two rough finishing operations require two separate chucking operations.
This invention relates to a brake rotor adapted for use in a vehicle brake system and a method for producing such a brake rotor. The brake rotor includes an inner mounting flange and an outer friction disc. The inner mounting flange includes an inner surface, an outer surface, and a center pilot hole formed therethrough. The outer friction disc includes an inner friction plate and an outer friction plate. The inner friction plate has an outer facing surface, an outer peripheral edge and an inner peripheral edge. The outer friction plate has an outer facing surface and an outer peripheral edge. The outer friction plate is connected to the inner mounting flange by a hat, and the hat has an outer facing surface and an inner facing surface. The inner mounting flange of the brake rotor includes a plurality of lug bolt receiving holes formed therethrough which are formed during the casting process. The method for producing the brake rotor comprises the steps of: (a) providing a mold; (b) casting a brake rotor in the mold, the brake rotor including an inner mounting flange and an outer friction disc, the inner mounting flange having a plurality of as cast lug bolt receiving holes formed therethrough; (c) removing the brake rotor from the mold; (d) performing at least one rough machining operation on the brake rotor; and (e) performing at least one finish machining operation on the brake rotor to thereby produce a finish machined brake rotor.